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http://www.knowsky.com/344358.html

http://www.cnblogs.com/greencolor/archive/2012/02/04/2337648.html

http://blog.sina.com.cn/s/blog_623200980100ie0o.html

http://blog.csdn.net/sj1900/article/details/5947630

http://jxm986.blog.163.com/blog/static/189051193200832101055226/